The driver may either be compiled as a module, or as a part of the kernel.
If you are running short on space for the kernel, it's probably advisable to compile it as module.

The SPI channel that is reserved for the ethernet on the Hammer Carrier board is SPI0.
The MMC interface uses SPI1. The current UBE driver may need to be re-configured if you are
going to use anything but the Hammer Carrier.